On this parts fiche the Dust Seal is the most specified component.
A sample from the products for the Front Brake Caliper (st1100l/m/n/p/r) include: Caliper Assy.,r.f, Cap,bleeder, Bolt,flange,8x32, Seal,piston.
The component with the lowest price in the FRONT BRAKE CALIPER (ST1100L/M/N/P/R) schematic is the Bolt,flange,8x32.